One of the greatest risks regarding transfusions of blood constituents, so-called blood transfusions, is a blood-group incompatibility between bag and recipient blood. The reasons for this are more often mix-ups than false determinations. For these reasons, so-called ABO identity tests are compulsory in some countries, which are carried out by the treating personnel, e.g. the nurse or the transfusing doctor, immediately before the transfusion at the patient's bed. These tests lead to additional stress of the station personnel which have little training in lab diagnostics and are amongst others rejected for this reason in some countries.
In certain countries as for example Germany or Austria, such an identity test is compulsory, however, only with regard to the recipient blood. In these countries, it is left to the respective hospital whether it carries out the identity test of the bag at the patient's bed or not. This is justified with the responsibility of the producer (blood bank) for the correct determination and designation of the bag blood. However, this does not prevent many hospitals from checking the bag blood type in the hospital lab once more and/or to carry out an ABO identity test at the patient's bed.